1. Field of the Invention
The present invention relates to a heat exchanger constructed by a plurality of plates forming inside fluid passages through which an inside fluid flows, and applicable to a refrigerant evaporator for a vehicle air conditioning apparatus.
2. Description of Related Art
Conventionally, as shown in FIGS. 28, 29A and 29B, a refrigerant evaporator for a vehicle air conditioning apparatus is constructed by laminating alternately a plurality of oval flat tubes and corrugated fins having louvers to increase an air side heat conductive area. Each oval flat tube is formed by connecting a pair of plates facing each other at the outer peripheries thereof. An assembling process of this heat exchanger becomes complicated because the corrugated fin is disposed between the adjacent oval flat tubes. That is, as the conventional heat exchanger needs a corrugated fin, it is difficult to reduce the manufacturing cost and the size of the heat exchanger.
In the air conditioning unit, the evaporator is generally formed into rectangular parallelopiped shape, as shown in FIG. 28. This is because it is difficult to form the outer shape of the corrugated fin into any shapes other than the rectangular parallelopiped shape for the reason that the corrugated fin is formed by press-forming a thin coil-like material into waved shape as shown in FIGS. 29A and 29B. As a result, the evaporator must be formed into the rectangular parallelopiped shape along the outer shape of the corrugated fin.